应用STS-PCR标记研究新疆布顿大麦的遗传多样性

利用22个来源于小麦(Triticum aestivum L.)和栽培大麦(Hordeum vulgare L.)的STS-PCR标记,研究了32份新疆布顿大麦(Hordeum bogdanii Wilensky)的遗传多样性.在这22个STS-PCR标记中,仅有3个标记的扩增产物经HinfⅠ、HhaⅠ、HaeⅢ和RsaⅠ 4种限制性内切酶消化后没有产生多态性DNA片段,而19个标记(占86.4%)和46种标记/酶组合(占52.3%)能够揭示材料间的多态性.在32份布顿大麦材料的88种STS-PCR标记/酶组合中,总共得到315条DNA片段,平均每个标记/酶组合能得到3.6条DNA片段.在这315条DNA片段中,共有123条片段(占39.0%)具有多态性,每一个多态性标记/酶组合能获得1～6条多态性DNA片段.STS-PCR标记揭示的32份布顿大麦的遗传距离变化范围为0.078～0.352,平均为0.198.根据STS-PCR标记的遗传距离矩阵,采用不完全加权算术平均数法(UPGMA)构建了32份布顿大麦群体间的遗传关系树状图,结果表明STS-PCR标记能将32份材料完全区分开来.同时,来源于同一地方的不同居群没有明显地聚类在一起,表明新疆布顿大麦的遗传多样性与其地理分布相关不紧密.     

茄子耐盐种质资源遗传多样性的SRAP和ISSR分析

利用SRAP和ISSR分子标记,研究了14份耐盐茄子种质资源的遗传多样性,结果表明,2种标记均能揭示材料间较高的遗传多样性,其中ISSR标记多态性略高于SRAP标记。在SRAP分析中,每对引物组合可扩增出8-15条DNA片段,平均为12．12条：26对SRAP引物组合共扩增出315条DNA片段,其中263条具有多态性,多态性比率为83．49％;材料间遗传相似系数变化范围为0．212～0．923,平均值为0．755。在ISSR分析中,每个引物可获得5～16条DNA片段,平均为10．87条;15个ISSR引物共扩增出163条DNA片段,其中141条具有多态性,多态性比率为86．50％;材料间遗传相似系数变幅为0．333-0．957,平均值为0．736。聚类分析表明,2种标记都能将供试材料完全区分开来,聚类结果具有一定的相似性,但也存在明显差异。Mantel相关分析表明,SRAP分析与ISSR分析的相关性达到极显著性水平（r=0．904,P〈0．01）。     

利用RAPD标记分析大麦种质资源的遗传多样性

利用RAPD标记对19份西藏近缘野生大麦材料、33份我国不同省市的地方品种以及8份国外引进大麦品种共60份大麦种质资源的遗传多样性进行检测.结果表明材料间遗传差异明显.32个RAPD引物中,有25个引物(占78.13%)可扩增出清晰且具多态性的条带,另外7个引物能扩增出1～3条清晰但无多态性的条带.每个引物可扩增出1～8条多态性带,平均为3.72条.32个引物共产生119条DNA片段,其中87条具有多态性,多态性比率(PPB)为73.11%,平均多态信息量(PIC)为0.434;每个位点平均有效等位基因数(Ne)为2.304;材料间遗传相似系数GS变化范围为0.757～0.981,平均值为0.871.19份来源于西藏的近缘野生大麦材料间GS值变幅为0.818～0.969,平均为0.892;33份我国栽培大麦地方品种间的GS值变化范围为0.783～0.981,平均为0.879;8份分别来自8个国家的栽培大麦品种间的GS值变幅为0.820～0.956,平均为0.882.根据RAPD标记分析的结果,对60份大麦种质资源进行聚类分析,在平均GS值0.871水平上60份大麦材料可聚为5类,聚类结果能在一定程度上反应材料的地理分布关系,但某些相同地理来源的材料也较分散地分布在整个聚类树中.本研究从分子水平上进一步证明了我国栽培大麦丰富的遗传多样性,是世界栽培大麦的遗传多样性中心之一.     

应用RAPD标记分析黑麦属品种的遗传多样性

四川农业大学小麦研究所侯永翠、郑有良、魏育明等研究人员对黑麦遗传多样性课题作了研究。他们采用随机扩增多态性DNA(RAPD)标记 ,对黑麦属 (SecaleL) 7个品种共 1 2份材料进行了遗传多样性检测 ,发现被检测材料间RAPD标记多态性较高 ,在 4 0个随机引物中 ,有 2 5个引物约占整个的 6 2 .5 %的扩增产物具有多态性。这 2 5个中共扩增出 1 6 7条带 ,其中 89条带约占 5 3.2 %具有多态性 ,每个引物可扩增出 1～ 1 0条多态性带 ,平均为 3～ 6条。RAPD标记遗传距离GD变异范围为 0 .1 382～ 0 .4 5 1 2 ,平均为 0 .2 71 2。通过聚类分析表…     

应用RAMP分子标记研究红花资源遗传多样性

采用RAMP（Random amplified microsatellite polymorphism）对原产于42个国家的84份红花材料进行遗传多样性分析。结果表明,被测材料间RAMP标记多态性较高。16个引物组合所产生的122条DNA扩增片段中,有118条具有多态性,PPB为96.7%。PIC的变化范围为0.580～0.978,平均值0.874。每个引物可扩增出4～11个DNA片段,平均获得7.6个DNA片断,其中7.4个具有多态性,遗传相似系数（GS）的变化范围0.338～0.907,平均值为0.665。基于GS的聚类结果可以将所有84份材料完全分开,并划分为6类,聚类结果与材料的地理分布有一定关系,来源于亚洲和美洲的材料多样性相对比较丰富,所有来自中国的材料被聚为一大类。据此认为,红花种质资源在分子水平上确实存在较大遗传差异,RAMP分子标记是评价红花资源遗传多样性的有效方法。     

羊草种质基因组DNA的AFLP多态性研究

羊草是禾本科牧草之王 ,在当前我国西部生态建设和草原畜牧业发展中发挥着重要作用。用AFLP方法对2 7份我国不同地区分布的羊草 (Leymuschinensis (Trin .)Tzvel)材料进行了基因组DNA多态性分析 ,8对AFLP引物组合在 2 7个不同羊草基因型中共扩增出 5 37条带 ,产生出的DNA片段大小分布在 75bp - 5 30bp之间。其中单态性带 89条 ,占 16 .6 % ,多态性带 32 9条 ,占 6 1.3%。平均每对引物组合扩增的DNA带数为 6 6 .13,总的多态性比率为 78.84%。AFLP多态信息含量PIC值分布于 0 .0 - 0 .5之间 ,平均PIC值为 0 .2 16 ,出现的PIC最大值 (0 .5 )约占AFLP标记的 8.5 % ,说明羊草基因组DNA的多态性比较丰富。以 5 37个AFLP标记为原始数据 ,根据Nei和Li的方法对 2 7份羊草材料进行遗传变异和聚类分析的结果表明 :羊草种内有高频率的遗传变异发生 ,且与地理分布和生态环境密切相关 ;2 7份羊草不同基因型被划分为四大类群 ,不同类群相互间的遗传距离相对较大 ,在树状图中表现为较远的亲缘关系。对羊草种内遗传变异发生的原因和品种的形成进行了初步讨论。     

用RAPD技术探讨冬青属苦丁茶的遗传差异、亲缘关系与分类地位

利用随机扩增多态性DNA (RAPD)技术对 2 2份冬青属苦丁茶不同种质材料的遗传变异进行了研究。 4 0个 10 bp的引物用于多态性检测 ,从中筛选出了 2 7个多态性良好的引物。用该 2 7个引物对上述 2 2份种质材料进行PCR扩增 ,共得到 4 45条DNA谱带 ,其中多态性带4 32条 ,占 97 0 8%。根据扩增结果计算了各份材料之间的遗传距离 ,并用UPGMA构建了聚类树状图。分析结果表明 :2 2份供试材料分成 4类 5组 ,第Ⅰ类为Ilexpentagona (分为A、B两组 :A组为新变种var mashanensisG .M .L .;B组为原变种var pentagona) ,第Ⅱ类为I kudingcha,第Ⅲ类为I latifolia ,第Ⅳ类为I cornuta ;第Ⅱ ,Ⅲ ,Ⅳ三类各有一组材料组成。物种的差异、亲缘关系以及同一物种内不同种质材料在起源地域上的差异均可从系统树中反映出来。RAPD分子标记的结果可作为判断冬青属苦丁茶种质资源材料的起源地域、遗传差异、亲缘关系以及种级水平和种下分类鉴定的重要参考依据     

基于AFLP标记的中国西藏近缘野生大麦遗传多样性分析

选取7对引物组合, 构建了36份西藏近缘野生大麦和4份栽培大麦的AFLP指纹图谱, 共获得清晰可辨的条带227条, 其中多态性带194条, 占85.46％, 从DNA分子水平显示出所试材料遗传多样性较为丰富。计算得各样品间的遗传距离(欧氏距离)介于2.646~10.488之间, 应用离差平方和法对供试材料的AFLP数据结果进行聚类, 建立了40份大麦材料的AFLP树状图, 聚类结果将40份材料分为5类, 进一步揭示出供试材料间遗传背景的相似性和复杂性。结合Nei’s遗传一致性分析结果, 发现近缘六棱野生大麦较之近缘二棱野生与栽培大麦的亲缘关系更近, 支持栽培大麦是从野生二棱大麦起源, 而野生六棱大麦是进化过程中的过渡类型的大麦系统发生观点。     

利用SRAP标记研究四川高原青稞育成品种的遗传多样性

利用SRAP(Sequence-related Amplified Polymorphism)分子标记技术, 对25份来自四川高原的青稞育成品种进行了遗传多样性研究。结果表明: 64对引物组合共检测出999条清晰条带, 62对可以获得多态性条带, 多态性引物组合占96.9%, 共产生225条多态性条带, 占总条带数的22.5%。64对引物组合共扩增出333种等位变异, 平均每个引物组合检测到5.20种等位变异。遗传多样性在0(me9/em14, me9/em15)~0.8928(me6/em18)之间, 平均为0.5126。聚类分析结果表明, 25份材料可分成A、B、C 3大类, 材料聚类与其来源地有明显的相关性。25份材料间的平均遗传距离较小(0.3240), 平均遗传多样性较低(0.5126), 遗传基础较为狭窄。     

四个鲫鱼品系线粒体DNA的限制性酶切分析

用差速离心和核酸酶消化法从红鲫 (C auratusredvar .)、湘鲫 [F1hybridsofredcruciancarp (♀ )×commoncarp (♂ ) ]、野鲫 (C auratusauratus)和白鲫 (C auratuscuvieri)的肝组织及白鲫的卵巢中提取和纯化线粒体DNA。用 9种内切酶 (EcoRⅠ、HindⅢ、PstⅠ、BglⅡ、BamHⅠ、XhoⅠ、XbaⅠ、SalⅠ和KpnⅠ )进行单酶酶解 ,经琼脂糖凝胶电泳分析 ,检测出PstⅠ、KpnⅠ和BglⅡ 3种酶在品系间存在限制性片段长度多态性 ,但并未检测出品系内的限制性片段长度多态性。计算出红鲫、湘鲫、白鲫和野鲫的mtDNA大小分别约为 16 19、 16 0 2、 16 6 0和 16 0 6kb。根据限制性酶切片段共享度 ,计算出 4个品系间的遗传距离 ,结果表明存在直接亲缘关系的红鲫与湘鲫之间的遗传差异最小 ,证实了红鲫与子代湘鲫之间mtDNA遵循母系遗传的特性。     

Metabolic rates,genetic constraints,and the evolution of endothermy

The metabolic distinction between endotherms and ectotherms is profound. Whereas the ecology of metabolic rates is well studied, how endotherms evolved from their ectothermic ancestors remains unclear. The aerobic capacity model postulates that a genetic constraint between resting and maximal metabolism was essential for the evolution of endothermy. Using the multivariate breeders’ equation, I illustrate how the (i) relative sizes of genetic variances and (ii) relative magnitudes of selection gradients for resting and maximal metabolism affect the genetic correlation needed for endothermy to have evolved via a correlated response to selection. If genetic variances in existing populations are representative of ancestral conditions, then the aerobic capacity model is viable even if the genetic correlation was modest. The analyses reveal how contemporary data on selection and genetic architecture can be used to test hypotheses about the evolution of endothermy, and they show the benefits of explicitly linking physiology and quantitative genetic theory.     

THE ACTION OF STABILIZING SELECTION,MUTATION, AND DRIFT ON EPISTATIC QUANTITATIVE TRAITS

For a quantitative trait under stabilizing selection, the effect of epistasis on its genetic architecture and on the changes of genetic variance caused by bottlenecking were investigated using theory and simulation. Assuming empirical estimates of the rate and effects of mutations and the intensity of selection, we assessed the impact of two‐locus epistasis (synergistic/antagonistic) among linked or unlinked loci on the distribution of effects and frequencies of segregating loci in populations at the mutation‐selection‐drift balance. Strong pervasive epistasis did not modify substantially the genetic properties of the trait and, therefore, the most likely explanation for the low amount of variation usually accounted by the loci detected in genome‐wide association analyses is that many causal loci will pass undetected. We investigated the impact of epistasis on the changes in genetic variance components when large populations were subjected to successive bottlenecks of different sizes, considering the action of genetic drift, operating singly (D), or jointly with mutation (MD) and selection (MSD). An initial increase of the different components of the genetic variance, as well as a dramatic acceleration of the between‐line divergence, were always associated with synergistic epistasis but were strongly constrained by selection.     

基因甘蔗：潜能、现状和前景

从基因中在甘蔗上的应用潜能、甘蔗遗传转化的方法及其成效、启动子及选择标记对基因表达和转化体筛选的效应,基因工程甘蔗的成就等几个方面进行综述评述,并提出了进一步的研究方向。     

Reassessing insurers' access to genetic information: genetic privacy, ignorance, and injustice

Many countries have imposed strict regulations on the genetic information to which insurers have access. Commentators have warned against the emerging body of legislation for different reasons. This paper demonstrates that, when confronted with the argument that genetic information should be available to insurers for health insurance underwriting purposes, one should avoid appeals to rights of genetic privacy and genetic ignorance. The principle of equality of opportunity may nevertheless warrant restrictions. A choice-based account of this principle implies that it is unfair to hold people responsible for the consequences of the genetic lottery, since we have no choice in selecting our genotype or the expression of it. However appealing, this view does not take us all the way to an adequate justification of inaccessibility of genetic information. A contractarian account, suggesting that health is a condition of opportunity and that healthcare is an essential good, seems more promising. I conclude that if or when predictive medical tests (such as genetic tests) are developed with significant actuarial value, individuals have less reason to accept as fair institutions that limit access to healthcare on the grounds of risk status. Given the assumption that a division of risk pools in accordance with a rough estimate of people's level of (genetic) risk will occur, fairness and justice favour universal health insurance based on solidarity.     

Invasiveness,chimerism and genetic diversity

Adaptation for invasiveness should comprise the capability to exploit and prosper in a wide range of ecological conditions and is therefore expected to be associated with a certain level of genetic diversity. Paradoxically, however, invasive populations are established by only a few founders, resulting in low genetic diversity. As a conceivable way of attaining high genetic diversity and high variance of gene expression even when a small number of founders is involved in invasiveness, I suggest here chimerism, a fusion between different individuals—a common phenomenon found in numerous phyla. The composite entity offers the chimeric organism genetic flexibility and higher inclusive fitness that depends on the joint genomic fitness of the original partners. The ability to form a chimeric entity is also applied to subsequent generations, and consequently, the level of genetic diversity does not decline over generations of population establishment following invasion.     

西藏特有植物砂生槐天然居群遗传多样性研究

采用等位酶淀粉凝胶电泳技术对西藏雅鲁藏布江中游砂生槐 (Sophoramoorcroftiana) 10个天然居群的遗传多样性进行了研究。 13个酶系统 2 4个酶位点 ( 46个等位基因 )的检测结果表明 ,砂生槐具较低的遗传变异水平。居群水平上的遗传多样性指标分别为 :多态位点百分率Pp =2 5 .0 %～ 37.5 % ,等位基因平均数Ap=1.3～ 1.7,平均期望杂合度Hep=0 .112～ 0 .16 9;种水平上的遗传多样性 (Ps=37.5 % ,As=1.9,Hes=0 .171)低于长寿命木本被子植物的平均值 (Ps=5 9.5 % ,As=2 .10 ,Hes=0 .183)。居群遗传结构的分析显示 ,10个居群中随机交配的偏差为FIS=- 0 .0 0 71,表明砂生槐在居群水平上存在轻微的杂合子过量现象 ,偏离了Hardy Weinberg平衡 ;FST=0 .1748,表明砂生槐是居群间分化较大的一类多年生木本植物 ,主要原因是环境恶化和人类活动干扰 (过度砍伐、放牧等 )导致其生境片断化 ,从而影响了居群间基因交流而造成基因流水平较低 (Nm =1.180 2 )。砂生槐高海拔居群H2 (谢通门 )、H31(江当 1)、H32 (江当 2 )、H5 (朗塞岭 )包含着绝大部分等位基因 ,显示了相对较高的遗传多样性水平 ,应加以保护和管理 ,作为砂生槐种质资源就地保存的基地。     

Genetic relationships between feral cattle from Chirikof Island, Alaska and other breeds

The origin of cattle on Chirikof Island, off the coast of Alaska, is not well documented. We assessed genetic differentiation of cattle isolated on Chirikof Island from several breeds commonly used for commercial production in North America including breeds popularly believed to have contributed to the Chirikof Island population. A set of 34 microsatellite loci was used to genotype Angus, Charolais, Hereford, Highland, Limousin, Red Angus, Salers, Shorthorn, Simmental, Tarentaise and Texas Longhorn cattle sampled from North America and the Chirikof Island population. Resulting F(ST) statistics for these loci ranged from 0.06 to 0.22 and on average, 14% of total genetic variation was between breeds. Whether population structure was modelled as a bifurcating tree or genetic network, Chirikof Island cattle appeared to be unique and strongly differentiated relative to the other breeds that were sampled. Bayesian clustering for multiple-locus assignment to genetic groups indicated low levels of admixture in the Chirikof Island population. Thus, the Chirikof Island population may be a novel genetic resource of some importance for conservation and industry.     

广东省中山市五桂山土沉香遗传多样性

土沉香(Aquilaria sinensis)是生产中药沉香的重要树种,现被列为国家二级重点保护野生植物。该研究通过采集该地区83株土沉香样品,利用限制性酶切位点相关DNA测序(restriction site-associated DNA sequencing,RAD-seq)方法获得的18个微卫星体作为分子标记,计算了五桂山土沉香种群的整体观测杂合度(observed-heterozygosity)、期望杂合度(expected-heterozygosity)、种群整体近交系数及其个体间的亲缘关系,并对种群可能经历的种群缩小或种群扩张状况进行了分析。结果表明:与同属其它物种以及同一生活史物种相比,五桂山地区土沉香遗传多样性略低(观测杂合度和期望杂合度分别为0.523和0.522),但种群整体处于随机交配状态(近交系数为-0.002)。瓶颈效应分析表明该种群没有经历瓶颈效应,且81.810%的个体间无亲缘关系,说明这一地区土沉香并非少数个体发育起来;种群扩张分析表明其种群大小有增长情形。综合这些结果可以看出,中山市五桂山土沉香种群整体遗传健康状况良好,较好地保存了该区域种质资源遗传多样性,为今后的保护和合理开发提供了优质资源储备。